Property Value

Type: System.TimeSpan
The duration of content closest to live that cannot yet be downloaded.

Remarks

Setting this property is equivalent to stating how long to delay before asking for the latest fragment in a live presentation, which effectively adjusts the perceived live position backwards. Increasing this value causes the live download position to back off from the real live position. This is done to avoid the possibility of asking for a fragment before it is available for download. The default value of 6 seconds means that the latest live content available on the server can be requested at the earliest 6 seconds later. Changes that are made to this value after the SmoothStreamingSource property has been set are disregarded.

The following diagram shows the stages of buffering and offsets.

The BufferingTime property specifies the duration of media content that will be downloaded before the SmoothStreamingMediaElement object begins to display any content. The LivePlaybackOffset property specifies the duration of media content backed off from the value of the LiveBackOff property (that is, the current live represented by the P:Microsoft.Web.Media.SmoothStreaming.SmoothStreamingMediaElement.LiveBackOff property) where downloading and playback begins. Setting the LivePlaybackOffset property enables faster startup through build-up of a portion or all of startup buffer specified by BufferingTime as fast as bandwidth will support. It creates a buffer against network jitter but increases the end-to-end latency.

As a result, the end-to-end latency on the client side (that is, how close playback is to live content that is available on the server) is at least the LiveBackOff value plus the larger of BufferingTime or LivePlaybackOffset value away from the live stream.